Objective To investigate the level of hepatitis B surface antibody (anti-HBs) among preschool children (aged 3‒6 years) and primary and secondary school students in Tonglu County, Zhejiang Province, to evaluate the effectiveness of hepatitis B vaccination, and to provide a basis for hepatitis B prevention and control in the region.

Methods As part of the 2023 Tonglu County Urban and Rural Residents Health Examination Program, blood samples were collected during health check-ups. Fingertip blood samples were obtained from preschool children, while venous blood samples were collected from primary and secondary school children. The anti-HBs levels in blood (positive + / negative -) were qualitatively tested using hepatitis B surface antibody test kits (latex method). The differences in anti-HBs positivity rates among different age groups were analyzed.

Results Between April 1, 2023 and June 30, 2023, a total of 52 919 individuals were surveyed, including 11 973 preschool children and 40 946 primary and secondary school students. The overall anti-HBs positivity rate was 39.74%, with the highest positivity rate observed among preschool children (60.20%). Age was negatively correlated with the anti-HBs positivity rate (P<0.001). No significant gender differences in anti-HBs positivity rates were observed. The anti-HBs positive rate in rural areas was higher than that in urban areas, with statistically significant differences across school grade groups (primary grades 1‒3, grades 4‒6, middle school, and high school) (P<0.001).

Conclusion The anti-HBs positivity rate among preschool and school-age children in Tonglu County decreases with age and remains relatively low. It is recommended to strengthen the monitoring of hepatitis B antibody levels and promote health education among preschool and school-age children. Children who have not completed the full hepatitis B vaccination should receive timely catch-up vaccination.